An automatic document feeder is an extremely useful adjunct to a flatbed copying machine, but often original documents are placed manually on the copy glass even though the automatic feeder is present. This mode of use, familiar to operators of such machines, is particularly useful for small documents such as snapshot photographs, receipts, checks, notes and so on.
In some such cases the copy may be made onto a small piece of printing medium, such as for example a piece of photo-quality glossy paper that matches the size of a snapshot being copied--for example, about 10 by 15 cm (4 by 6 inches). Alternatively, the copy may be made onto a full-size piece of printing medium, whose excess area is later either trimmed away or ignored.
When original documents are placed on a copy glass manually--either because the documents are small or for other reasons (such as reluctance to feed a valuable document through an automatic feeder)--the feeder is typically hinged up out of the way, for access to the copy glass during placement of the original on the glass. The feeder is then lowered again before copying begins. Thus the feeder is not used as a feeder, i.e. it is not really in service, and at most acts as a backup panel in lieu of a lightweight cover.
Typically portions of an automatic document feeder apparatus are visible to the scanning stage of a copier when a small document is in place on the glass. These portions most commonly include document-moving rollers, and so-called "roll-off" areas (which will be introduced below); and may also include document-moving belts and the like. Such visible apparatus portions give rise to image data, and the overall image data array includes these data together with the desired image data for the document.
Naturally the images of the apparatus portions are then copied, along with the desired document image, onto the printing medium--if the printing medium is large enough to intercept the ink generated by the apparatus-portion component of the data. Such images of the apparatus portions would be objectionable to most or many final users of the copies.
If the printing medium is not large enough to catch this spurious inking, then the ink is instead applied to some portion of the printing-stage mechanism in the copier--thereby soiling the mechanism. In time, such misapplied ink usually causes some sort of trouble, depending on the type of mechanism in use.
For example, in one inkjet-type copier with which we are familiar the ink accumulates on a part of the mechanism known as the "print pivot", and is later transfered to subsequent copies. The resulting spoiled, ink-streaked copies would be objectionable to almost all final users.
If not cleaned away, in time the ink may actually come to interfere with mechanical operation of the mechanism itself. Analogous visual and mechanical problems may be expected with other kinds of copiers to which our invention may be applicable, such as for instance thermal-transfer or dot-matrix types.
Another somewhat related problem in copiers is the appearance of shadows around the edges of output images, particularly edges that are not fully pressed down against the copy glass. Depending on the geometry of the backup panel, such shadows may appear along edges of the document image that correspond to edges of the original document which are positioned near the outer envelope of the copying machine; or in other cases may appear even along edges of the image that nearer the center of the apparatus. In any event these shadows are usually considered unaesthetic and undesirable.
We are aware of one scanner/copier, available from the Canon Corporation, that has a so-called "image replicate" operating mode. This mode, when specifically invoked by an operator, scans an undersize document, automatically selects framing for the document, and then prints as many images of the document as possible onto a single page of printing medium. For instance a thumbnail photo about 2 by 4 cm (roughly 11/2 by 21/2 inches) may yield twenty actual-size copies on A4 paper.
Since this system relies upon operator commands to initiate its "replicate" mode, and is not particularly addressed to the context of out-of-service document feeders, it fails to solve the problems described above.
A scanner of the Hewlett Packard Company, available under the model designation "ScanJet 5p" is able to automatically find correct framing for an undersize document. That system, however, is not a copier--and furthermore stops, after selecting tentative framing, to wait for an operator's confirmation or adjustment of that framing. Therefore the ScanJet 5p does not resolve the problems under discussion.
Therefore quality defects as described above remain, impeding the achievement of uniformly excellent printing by inkjet copiers, and some other types of copiers as mentioned earlier. Thus important aspects of the technology used in the field of the invention remain amenable to useful refinement.